OBJECTIVES: I. Evaluate the relative contributions of factors that may lead to weight gain in breast cancer patients receiving adjuvant chemotherapy. Factors examined include: Hormonal and growth factor status (follicle stimulating hormone, total, bound, and free estradiol, androgens, sex hormone binding globulin, thyroid hormones, prolactin, insulin-like growth factors I and II, and plasma leptin) Factors affecting energy intake or expenditure (oral intake, physical activity, and resting metabolic rate) Psychological factors (depression and quality of life) II. Evaluate the effect of chemotherapy on hormonal and growth factor status in these patients.